For the purpose of sufficiently explaining the current level of the art related to the present invention, descriptions of all patents, patent applications, patent gadgets, scientific literatures and the like quoted or specified herein are incorporated herein by reference in its entirety.
Examples of a technology related to network mobility include a technology by Internet Engineering Task Force Network Mobility Working Group (IETF NEMO WG). This art will be explained hereafter referring to IETF Internet Draft (draft-ernst-nemo-terminology-01.txt) as shown in FIG. 18. The internet 002 is connected with a correspondent node 001, a home agent 003 and an access router 004. The home agent 003 is further connected to a network 005. The access router 004 is also connected to the network 006 which is connected to a mobile network 011.
The inside of the mobile network 011 is configured by a mobile network node 009, a mobile network node 010 and a mobile router 007, each of which is connected to each other through a network 008. The mobile network 011 is connected to the external network 006 via the mobile router 007 as a gateway, and is accessible to the Internet 002 via the access router 004.
The home agent 003 belongs to a home network for the mobile network 011. A home network 021 is a subnet including a Home Address (HoA) of the mobile router 007. All mobile network nodes that belong to the mobile network 011 have an address of the home network 021. The mobile network 011 is a network where all component nodes are mobile together.
In the configuration as described above, the conventional art operates as follows.
First, when the mobile network 011 moves, the mobile router 007 that serves as a connection node with the outside acquires a Care of Address (CoA) acquired in the home agent 003 that belongs to a subnet managed by the access router 004, and notifies the home agent 003 of the acquired CoA.
This address registration process operation enables the home agent 003 to understand a position of the mobile router 007.
Thereafter, when a packet addressed to an address belonging to the home network 021 reaches the home network 021, the home agent 003 receives the packet on behalf of it.
The home agent 003 uses the received packet as a payload to encapsulate it by a header with CoA as the destination and an address of CoA as the source, and transfers the packet to CoA. The mobile router 007 that has received the encapsulated packet retrieves a packet corresponding to the payload portion, and transfers it to the mobile network node, which is an actual destination.
In a similar manner, the packet transmitted from the mobile network node is encapsulated by a header with an address of the home agent 003 as the destination and CoA as the source at the mobile router 007, and is transferred to the home agent 003. The home agent 003 that has received the encapsulated packet retrieves a packet corresponding to the payload and transfers it to the actual destination. Such an interactive tunnel allows the mobile network 011 to logically exist as a subnet which is connected to the network 005 managed by the home agent 003. Accordingly, the mobile network node is capable of communicating with the correspondent node 001 without detecting mobility.
The mobile network 011 repeats an address deletion process operation from and address registration process operation in the home agent 003 every time the network is moving, so as to re-configure the interactive tunnel.
Accordingly, it is possible to continue communication also when the network is moving, without this move being detected by the mobile network node.
Moreover, the mobile router 007 is capable of using a plurality of communication interfaces for connecting to the external network. A sub-interface is used for a back-up use when the main interface breaks down.
However, in a communication method studied in the conventional NEMO, a problem is caused where the bandwidth is not wide enough for the traffic that is generated when the access line used the mobile router uses a narrow-band line.
Meanwhile, there is a service in which line with a broad band is configured by bundling access lines of the same service.
An example of the service is disclosed in the AirH” 128 kbps service internet (in the URL: http://www.ddipocket.co.jp/data/i_air.html) by DDI Pocket Inc. Although a specific configuration of this service is unknown, this company provides a packet communication service at 128 kbps, by using an ISDN line from the wireless base station free from jitter and bundling at most four 32 kbps-lines.
Meanwhile, in order to save the wireless resource, what is common currently is that a wireless network operator, upon the request from the user to establish the line, executes a connection admission control by comparing the wireless resource status in the cell at that point and the wireless resource amount required for the line.
However, the conventional art represented by the aforementioned IETF Internet Draft (drafternst-nemo-terminology-01.txt) is used for a line exchange network.
Therefore, there are some cases where a plurality of access lines containing a same or different types of services and of which quality fluctuates in time are bundled via a packet exchange network. In this case, where there is no means for combining optimal routes (or addresses) as the destination and the route (or address) to be used is randomly determined, packets cannot be properly transmitted and many packets requiring re-transmission are generated. Accordingly, though the bundled lines cannot be effectively used, and thus the conventional art cannot be applied to the packet exchange network as it is. Note that, the service herein refers to a communication service provided by a telecommunications carrier hereinafter merely referred to as carrier). Moreover, different types of service refers not only to services provided by different carriers, but also a service with different communication systems or billing systems even if provided by a same carrier.
Moreover, when the network is moving in a wide area such as a network configured in a vehicle, communication is not always made not only within one service area. Instead, communication is more often made while the user is moving among several service areas. In this case, the same service is not always provided in the place to which the user has moved, or the existing service cannot always be maintained due to a change of an external environment. Therefore, there is a risk that communication may be interrupted or the communication band may substantially decrease.
For example, as shown in FIG. 37, the following case is assumed. The carrier X provides services x1 and x2 in an area A, the carrier X provides the service x1 and a carrier Y provides a service y1 in an area B, and the carrier Y provide the service y1 and a service y2 in an area C. A user of a network N configured in a train subscribes to the services x1 and x2 provided by the carrier X and the services y1 and y2 provided by the carrier Y The network N moves in the sequence of the area A, area B and area C.
In this case, the network N performs communication using the services x1, x2 provided by the carrier X in the area A. However, when the network N has moved to the area B, the service x2 has become unusable, whereby the amount of the data that can be transmitted decreases. Furthermore, the network N having moved to the area C has become unable to get the service provided by the carrier X, which disables the communication. Though the network N also subscribes to the service provided by the carrier Y, the conventional art is not capable of combining services provided by the different carriers, that is, the service provided by the carrier X and the service provided by the carrier Y. Therefore, the user is not able to get a service provided by the carrier Y at a place to which the user has moved. Moreover, the conventional art represented by the aforementioned IETF Internet Draft (drafternst-nemo-terminology-01.txt) has no means for saving the wireless resources without replying on a network operator.